It is previously known in the art to thermoform a pouring spout on a liquid package from, for example, Swedish Patent Application No. SE 9100921-7. According to this method, a pouring spout is formed from a sheet of thermoplastic material, the spout being enclosed by an outer closure portion, a so-called screw cap.
The thermoplastic material sheet may comprise the entire upper side of a package which otherwise consists of a packaging laminate with a core of paper or paperboard to which different layers are laminated, the outermost layer being thermoplastic. The cross section of the package may be circular or rectangular. The thermoplastic material sheet may also consist of a minor portion, covering a cut-out piece from a conventional laminate package so that it is welded in place against the inside of the laminate package of thermoplastic material. One such package may, for example, be a so-called gable-top package.
In one of the above-described package types--which is finished inasmuch as it consists of side walls and a top wall, a pouring spout is formed in the top wall. A forming tool is passed through the as yet incomplete bottom of the package, and an outer closure portion (a so-called screw cap) is lowered from the upper side of the package, the closure portion serving as a mould for forming the pouring spout. When the pouring spout has been formed in this way, the upper portion of the pouring spout is sealed in place against the inside of the upper closure portion. This sealing or closure is intended to be broken when the package is opened. However, this method gives no external indication that the package has been tampered with or illicitly opened so that its contents might have been manipulated. Since this applies to packages for sensitive foods, it is often desirable to provide the package with an opening arrangement of the type which immediately indicates whether or not the package has been improperly opened before reaching the consumer.